Cahokia

Cahokia was a Mississippian city on the Mississippi floodplain in present-day Illinois, known for its earthen mounds. By 1337 its population had fallen sharply from its peak around 1100.

By 1350 Cahokia had been abandoned, and the causes remain disputed. Archaeological evidence indicates that the wider area’s population later rebounded, reaching a peak in 1650. The city’s original name was lost; French explorers later named the ruins after the Cahokia, an Illiniwek people who lived nearby.